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In this work, a series of fluorinated core-shell polyacrylate latex pressure sensitive adhesives (PSAs) were successfully synthesized through monomer-starved seeded semi-continuous emulsion polymerization. Specifically, (meth)acrylate monomers were employed as the main materials, with dodecafluoroheptyl methacrylate (DFMA) were used as modified monomer. The impact of fluorine monomer DFMA on the resulting core-shell latex and PSA properties was thoroughly examined. FTIR analysis confirmed the successful incorporation of DFMA into the latex copolymer through emulsion polymerization. TEM images illustrated that the morphology of latex particles exhibit a distinct core-shell structure. The results also showed that with the addition of DFMA, the water absorption and water whitening of the latex films decreased, while the water contact angle and thermal stability are improved. Interestingly, the latex films with DFMA added to the shell phase exhibit a larger WCA value when compared to those with DFMA in the core phase, further confirmed by XPS results. Finally, the adhesive properties of the fluorinated core-shell acrylate PSA were evaluated. The results of shear strength and gel content demonstrate that the prepared PSA exhibits excellent cohesive properties. Thus, this work could present a feasible strategy for optimizing the comprehensive properties of acrylate latex PSAs. [ABSTRACT FROM AUTHOR]

Colloid silica nanoparticles were hydrophobic modified by γ-methacryloxypropyl trimethoxysilane (MPS) for the encapsulation into polymer. The alkoxysilane-functionalized core-shell latexes were successfully synthesized via miniemulsion copolymerization of the butyl acrylate, styrene with MPS as the functional monomer in the presence of the modified silica. When these latexes dried at room-temperature, the post-cross-linking occurred due to the alkoxysilane groups on the particle surface and lead to the formation of the films. The morphology of the nanocomposite latexes and the mechanical properties, thermal properties, fire-resistant, optical properties and micro-structure of the resulted films were characterized and discussed. Scanning electron microscope result showed most of the nanoparticles dispersed homogeneously in the polymer matrix when the content of MPS-silica was 10%. However, when the content of MPS-silica nanoparticles was beyond 10%, the aggregation of the nanoparticles became obvious. The tensile test showed that the stress at break increased a lot with the increase of silica content. The thermal and fire-resistant behaviors of the nanocomposite films were improved greatly by the incorporation of silica particles. The optical test showed that the hybrid film was comparable to the pure polymer film at around 84% transmittance. [ABSTRACT FROM AUTHOR]

The paper deals with a novel flame retardant and its application in waterborne coatings. The flame retardant was synthesized from hexachloro-cyclo-triphosphazene by nucleophilic substitution with allylamine. Functionalized emulsion copolymers bearing in the structure hexaallylamino-cyclo-triphosphazene were prepared by the semicontinuous emulsion polymerization. The latexes were used as the main component of transparent coating systems cured by melamine formaldehyde resin. The incorporation hexaallylamino-cyclo-triphosphazene did not affect transparency, flexibility, and toughness of resulting coatings and increased their flame stability in terms of the amount of smoke release and maximum average rate of heat emission indicating a slower flame spread during the material combustion. [ABSTRACT FROM AUTHOR]

In this study the synthesis of a novel flame retardant based on halogenophosphazene derivative and its application in waterborne coatings based on self-crosslinking latexes was investigated. Hexaallylamino- cyclo -triphosphazene was synthesized by nucleophilic substitution of hexachloro- cyclo -triphosphazene with allyl amine. Latexes of functionalized core-shell particles bearing in the structure hexaallylamino- cyclo -triphosphazene molecules were prepared by the semi-continuous non-seeded emulsion polymerization of methyl methacrylate, butyl acrylate and methacrylic acid as main monomers. For interfacial crosslinking, diacetone acrylamide was copolymerized into the shell layer of latex particles to provide sites for subsequent reaction with adipic acid dihydrazide. The incorporation hexaallylamino- cyclo -triphosphazene did not affect transparency, flexibility, toughness and adhesive properties of resulting coatings. Moreover, the presence of the novel flame retardant decreased water sensitivity and increased the flame stability of coatings in terms of reduced total heat release, decreased amount of released smoke and drop in maximum average rate of heat emission which indicates a slower flame spread during the material combustion. [ABSTRACT FROM AUTHOR]

Self-cross-linkable latexes of core–shell microgel particles were synthesized by the emulsion polymerization of acrylic monomers. The molar mass of copolymers forming the shell layer was gradually reduced by isooctyl 3-mercaptopropionate included in the synthesis of the shell layers. The molar mass distribution of latex particles was determined using size exclusion chromatography and asymmetric flow field-flow fractionation, respectively, both separation methods being coupled with a multiangle light scattering detector. The results confirmed theoretical predictions and described empirically the effects of molar mass of the shell layer copolymer on decreasing the minimum film-forming temperature and influencing the end-use properties of coatings. [ABSTRACT FROM PUBLISHER]

The modification of the bagasse cellulose fiber by the adsorption of cationic poly latex with core–shell structure on fiber surfaces was conducted in attempt to enhance the interfacial compatibility between hydrophilic fibers and the hydrophobic substrates for various applications. A two-step semi-batch emulsion polymerization was employed for constructing core–shell latex. TEM and dynamic light scattering (DLS) analysis indicated that the core–shell latex possessed a broad particles size distribution, which led to the adsorption of the latex on fiber proceeding via two-stage equilibrium mainly due to the effect of latex particle size. The pseudo-first-order kinetic model was appropriate for the description of the kinetics of the first stage equilibrium at high latex concentration and the entire adsorption process at low concentration. In contrast, the pseudo-second-order kinetic model fitted the second equilibrium at high latex concentration well. The activation energy calculated suggested that the number of activated molecules was increased as the increase of adsorbent concentration, which might change the dominant adsorption mechanism. This also addressed the reasons for the abnormal adsorption behavior with the extra-added emulsifier. In addition, the surface property of the modified cellulose fibers was also investigated via contact angle measurements. The results proved that the cellulose fiber modified with the latex became hydrophobic, allowing the as-modified cellulose to be potential reinforcements for biocomposite. Finally, the adsorption mechanism was proposed according to the adsorption process mainly governed by electrostatic interactions, hydrogen bond, π–π stack and chain entanglement. [ABSTRACT FROM AUTHOR]

In this study, we have successfully introduced siloxane monomer, 2,4,6,8-Tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (V 4 ) into the shell of silica/poly(methyl methacrylate-butyl acrylate) (SiO 2 /P(MMA-BA)) core–shell nanocomposite colloids via in-situ emulsion copolymerization. The obtained nanocomposite films with 50% silica content all show excellent transparency (nearly 100% transmittance in visible range) and film-forming property (T g under 30 °C). More importantly, the addition of V 4 can significantly increase the weathering durability of the film by improving the water repellency, cross-linking degree and UV-blocking property of the film. [ABSTRACT FROM AUTHOR]

A series of self-cross-linking fluorinated polyacrylate latex particles with core-shell structure were successfully prepared by one-step miniemulsion polymerization of methyl methacrylate (MMA), butyl acrylate (BA), dodecafluoroheptyl methacrylate (DFMA), and γ-methacryloxypropyl triisopropoxidesilane (MPS). The core-shell structure of the latex particles was confirmed and the latex films were characterized. Results showed that the latex films not only showed enhanced thermostability but also exhibited good hydrophobic property with the incorporation of a small amount of MPS (below 5 wt% of monomers). This core-shell fluorine/silicone-containing polyacrylate latex could potentially be used for developing advanced multifunctional protective coatings such as antiwetting, anti-icing, antifogging, and anticorrosion. [ABSTRACT FROM AUTHOR]

The effect of reducing the molar mass of the shell layer of core–shell latex particles on film-forming and final coating properties of self-crosslinking latexes was investigated. Latex particles were prepared by the semi-continuous non-seeded emulsion polymerization of methyl methacrylate, butyl acrylate and methacrylic acid as main monomers. The particle core was slightly cross-linked (using a constant amount of allyl methacrylate as a comonomer) to prevent the copolymers forming the core phase from migration into the shell phase. For interfacial cross-linking, diacetone acrylamide was copolymerized into the shell layer of latex particles to provide sites for subsequent reaction with adipic acid dihydrazide. The molar mass of copolymers forming the shell layer was systematically varied by isooctyl 3-mercaptopropionate chain transfer agent included in the synthesis of each of the shell layers and the molar mass distribution was determined using size exclusion chromatography coupled with a multi-angle light scattering detection. Fundamental properties of latexes and cast films were systematically compared. These properties included minimum film-forming temperature, pendulum hardness, adhesion, impact resistance, stress–strain properties as well as the characterization of water absorption. The results confirmed theoretical predictions and described empirically the effects of reducing the molar mass of the shell layer copolymer on final properties of coating films. [ABSTRACT FROM AUTHOR]

Designed appropriately, multiphase soft-core/hard-shell latex particles can achieve film formation without the addition of a coalescing aid, while preserving sufficient film hardness. Achieving optimal performance in these materials requires an understanding of how particle morphology affects film formation and stress development in the film. In this study, soft-core/hard-shell latex particles with different shell ratios, core and shell glass transition temperatures ( Ts), and particle sizes (63-177 nm) were synthesized using a two-stage emulsion polymerization. The film formation behavior of the composite particles was investigated with cryogenic scanning electron microscopy, atomic force microscopy, and measurements of the minimum film formation temperature (MFFT). Results show that film formation was enhanced for particles with thinner hard shells, smaller particle size, and a smaller difference in T between the core and shell polymers. For example, the MFFT decreased and the particle deformation increased for particles with thinner shells and smaller particle sizes. Stress development during drying was characterized using a cantilever beam bending technique. A walled cantilever design was used to monitor stress development without the complication of a lateral drying front. The film formation behavior and stress development correlated well with practical paint properties like scrub resistance and gloss. [ABSTRACT FROM AUTHOR]

Highlights: [•] PSA/PSi core–shell latexes synthesized through seeded emulsion polymerization. [•] Morphology characterized through TEM, DLS, and SEM-EDXS. [•] DMA analyses of the hybrid polymer show a broader effective tan δ. [•] White paints made from hybrid polymers show excellent weatherability under UV and outdoor exposure. [ABSTRACT FROM AUTHOR]

Highlight: [•] Present a new strategy for fluorosilicone copolymers core–shell latexes. [•] The effect of 6FA, 3FMA, 6FMA and 12FMA monomers on the latex is investigated. [•] The longer side chains of 12FMA contribute much to the lower surface free energy. [•] P(D4/D4 V)/p(BA/MMA/12FMA) latex gives a lower wettability and water absorption film. [Copyright &y& Elsevier]

Highlights: [•] A fluorinated isocyanate acrylic monomer (FA) was synthesized. [•] Core–shell poly(fluorine acrylate) latexes with fluorine in shell were prepared and characterized. [•] Increasing FA monomer in emulsion polymerization affected latex film surface roughness and hydrophobicity. [•] Water contact angles increased with film surface roughness. [•] The FA monomer could enhance the abrasion resistance of the polymer films. [Copyright &y& Elsevier]

Highlights: [•] Adsorption of cationic latex provides a novel approach for modifying CTMP fibers. [•] As-modified CTMP is very effective in reinforcing polypropylene-based biocomposite. [•] Mechanical properties were improved significantly at a low dosage of latex addition. [•] Modified cellulose fiber improved the computability between fiber and PP matrix. [•] Synergetic effect on promoting the crystallization of PP was observed. [ABSTRACT FROM AUTHOR]

Modified micro-emulsion polymerization was successfully used to synthesize a kind of ambient temperature self-crosslinking core-shell emulsion, consisting of polyacrylate core and vinyltriethoxysilane (VTES) modified polyacrylate shell, by varying the ratio of soft monomer (BA) and hard monomer (MMA) which is different in the core and shell. The emulsion and its film formed at ambient temperature were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Core-shell structure was clearly shown in TEM micrographs, and two distinct glass transition temperatures ( T) were confirmed by DSC analysis. Lower T of core phase analyzed by DSC and self-crosslinking properties of VTES characterized by crosslinking degree cause latex particles form continuous film at ambient temperature. Thermal and mechanical properties and the surface properties of the latex films were also investigated. Results showed that the core-shell latex films containing 5 and 7.5 % VTES exhibited higher thermal stability, better mechanical properties, higher contact angle, and water resistance compared with pure polyacrylate film. [ABSTRACT FROM AUTHOR]

A core-shell latex comprising poly(butyl acrylate) as core and poly(styrene-methyl methacrylate) as shell was synthesized by emulsion polymerization using allyloxy nonylphenoxy propanol polyoxyethylene ether ammonium sulfonate (ANPS) as emulsifier. Transmission electron microscope, differential scanning calorimeter, and thermogravimetric analyses suggested the prepared latex had a core-shell structure. The particle size of the core-shell latex was about 102.8 nm with a molar ratio of butylacrylate, methyl methacrylate, and styrene at 6 : 2 : 2, a mass ratio of ANPS and monomers, ammonium persulfate and monomers at 15% and 1.0%, respectively. The core-shell latex showed high centrifugal stability and excellent freeze-thaw stability. The clogging nozzle rate of the pigmented ink containing 20 wt % core-shell latex was small, whereas the printed fabrics with this pigmented ink exhibited high rub and washing fastness. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to prepare a kind of novel multi-layer core-shell latex, and to evaluate the effect of the preparation methodology. Design/methodology/approach – Core-shell poly(siloxane)/polystyrene/polymethyl methacrylate (PSi/PSt/PMMA) latex particles were prepared by seeded-emulsion polymerisation with three stages. The core of cured PSi was prepared with octamethyl cyclotetrasiloxane (D4) and tetraethoxysilane (TEOS) by co-condensation. Using vinyltriethoxysilane (VTEOS) as coupling agent, functional PSi particles with vinyl groups on surfaces were prepared by hydrolysis and condensation of VTEOS in core formation stage. Then, the functional PSi particles were used as seeds to copolymerise with styrene and methyl methacrylate sequentially in shell stage I and stage II to form PSi/PSt/PMMA latex particles. Findings – FTIR, TEM, DSC and XPS showed that the PSi/PSt/PMMA latex particles had multi-layer core-shell structure with cured PSi as core, PSt as shell I and PMMA as shell II. Research limitations/implications – In the present work, PSi/PSt/PMMA latex particles having multi-layer core-shell structure with cured PSi as core, PSt as shell I and PMMA as shell II were prepared. This methodology can be employed to prepare new functional materials for various applications. Practical implications – Multi-layer core-shell particles offer a new area of material science that has wide applications in coatings or modified polymer materials production. Originality/value – The method developed in the study reported in this paper provides a new strategy to develop new types of core-shell materials with multi-layer structure. [ABSTRACT FROM AUTHOR]

Abstract: Multilayer core–shell poly (styrene-butyl acrylate) latex particles were synthesized via semi-continuous emulsion polymerization, and the process was monitored by a dynamic laser scattering (DLS). The layers of the latex particles were designed to have progressively decreasing glass transition temperatures (T g) from the core (layer 1) to the outmost shell (layer 4), which was achieved by varying the mass ratio of butyl acrylate (BA) to styrene (St) in the synthesis of each layer. Divinylbenzene (DVB) was added as the crosslinking agent in each layer except for the outmost layer in order to ensure that a continuous film can be formed at room temperature. The damping properties of the formed films as well as the influences of synthesis variables, including the content of DVB added in the internal layers (i.e., layers 1, 2, and 3), the total mass ratio and sequence between layers 3 and 4, and the T g of each layer were studied by dynamic mechanical analysis (DMA). The results showed that four-layer core–shell latex particles with proper DVB content in each layer exhibited the best damping properties, with a broad effective damping range (tan δ >0.3) ranging from −12.0°C to 97.2°C. The widening of the damping peak can be explained by the formation of a gradient IPN structure in latex particles. Furthermore, the morphology of the formed films was studied by AFM in tapping mode. [Copyright &y& Elsevier]

The main aim of this research is to prepare environmentally friendly waterborne traffic-marking paint, which has fast dry, wear resistance, and long-term durability. The crosslinkable monomers are selected to co-polymerize with acrylate, then a core/shell latex with hard core and soft shell is obtained. The functional latex is blended with nano-silica, polyfunctional amine, functional pigments, and filler to obtain an excellent environmentally friendly traffic-marking paint. And, the latex polymer is further modified with multifunctional enamine silane coupling agent to enhance the wear, water resistance, and dry speed of the traffic paint. The reactive hydroxyl groups on the surface of nano-silica can react and crosslink with hydroxyl, nitrogen atoms, or carboxyl groups of binder, which can form a dense crosslinking network, enhance the crosslinking density, and bond strength. The above results can meet the special needs of the traffic-marking paint. [ABSTRACT FROM AUTHOR]

A series of core-shell polyacrylate latexes with different fluorine/silicone monomer concentrations were prepared successfully by seeded emulsion polymerization. Dodecafluoroheptyl methacrylate and perfluorooctyl methacrylate with different fluorinated side chains were employed as fluorinated monomers, and γ-methacryloxypropyl triisopropoxidesilane (MAPTIPS) was used as a silicone-containing monomer as well as a self-cross-linking agent. The morphology and chemical structure of the latexes were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and differential scanning calorimetry, and the self-stratification properties of the latex film were verified by X-ray photoelectron spectroscopy and static contact angle measurement. The results showed that the fluorine/silicone-containing polyacrylate latexes presented a uniformly spherical core-shell structure, and the latex films displayed a preferential distribution of fluorinated composition near the surface, which was more remarkable with the synergism effect between the fluorine monomer and MAPTIPS. Additionally, the hydrophobicity and oleophobicity of the latex films exhibited high relevance with the fluorine/silicone monomer concentrations as well as the fluorinated side-chain structure. [ABSTRACT FROM AUTHOR]

A core-shell latex based on methyl methacrylate, n-butyl acrylate, and methacrylic acid was synthesized, and the core of which was modified by hydroxyl-containing poly(dimethyl siloxane). Glycidyl methacrylate was empolyed as one of monomers in the shell and served as a cross-linker when the core-shell latex was used as an binder of the pigment printing. The chemical structure of the copolymer was characterized by infrared spectrum. The stucture and the particle size of the core-shell particles were characterized by transmission electron microscopy, nanoscale granularity analysis, and differential scanning calorimetry. The latex was used as a binder in pigment printing of fabrics. [ABSTRACT FROM AUTHOR]

Abstract: Novel surfactant-free core–shell hybrid latexes have been successfully synthesized by seeded emulsion polymerization of 10–60wt% vinyl monomers (styrene and butyl acrylate) in the presence of a soybean oil-based waterborne polyurethane (PU) dispersion as seed particles. The soybean oil-based waterborne polyurethanes, synthesized by reacting isophorone diisocyanate with methoxylated soybean oil polyols and dimethylol propionic acid, form the latex shell, serve as a polymeric high molecular weight emulsifier, while the vinyl polymers form the core. The structures and thermal and mechanical properties of the PU dispersions and the resulting core–shell latexes have been characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and measurement of the mechanical properties. The core–shell hybrid latex films show a significant increase in thermal stability and mechanical properties when compared with the pure polyurethane films, and exhibit a change in mechanical behavior from elastomeric polymers to tough and hard plastics, due to grafting and crosslinking in the hybrid latexes. [Copyright &y& Elsevier]

This work is focused on a facile route to prepare a new type of nylon 6-based nanocomposites with both high fracture toughness and high strength. A series of nylon 6-matrix blends were prepared via melting extrusion by compounding with poly (methyl methacrylate- co-butadiene- co-styrene) (MBS) or poly(methyl methacrylate- co-methylphenyl siloxane- co-styrene) (MSIS) latices as impact modifier and diglycidyl ether of bisphenol-A (DGEBA) as compatibilizer. Layered organic clay was also incorporated into above nylon 6 blends for the reinforcement of materials. Morphology study suggests that the MBS or MSIS latex particles could achieve a mono-dispersion in nylon 6 matrix with the aid of DGEBA, which improves the compatibilization and an interfacial adhesion between the matrix and the shell of MBS or MSIS. High impact toughness was also obtained but with a corresponding reduction in tensile strength and stiffness. A moderate amount of organic clay as reinforcing agent could gain a desirable balance between the strength, stiffness and toughness of the materials, and tensile strength and stiffness could achieve an improvement. This suggests that the combination of organic clay and core-shell latex particles is a useful strategy to optimize and enhance the properties of nylon 6. Morphology observation indicates that the layered organic clay was completely exfoliated within nylon 6 matrix. It is found that the core-shell latex particles and the clay platelets were dispersed individually in nylon 6 matrix, and no clay platelets were present in MBS or MSIS latex particles. So the presence of the clay in nylon 6 matrix does not disturb the latex particles to promote high fracture toughness via particle cavitation and subsequent matrix shear yielding, and therefore, provides maximum reinforcement to the polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Abstract: Composite latex of P(St-co-BA)/P(MMA-co-BA) was prepared by two-step semi-continuous emulsion polymerization under starved conditions. Optical properties, water resistance and heat aging process of the film formed by the composite latex were examined. It was revealed that annealing temperature played an important role on the structure of the composite latex film. The surface of the film prepared at room temperature was very rough. Many micro-cracks were observed both on the surface and inside of the film. Increase of annealing temperature assisted film formation. There was a critical temperature at which the film properties, such as water resistance and transparency, were significantly improved. However, it was worth to note that phase rearrangement had occurred when the annealing temperature was higher than critical temperature. Micro-pinholes and micro-cracks were detected on the surface of the film. Meanwhile, the properties of the film, such as transparency and water adsorption, became remarkable deteriorated. [Copyright &y& Elsevier]

Well-defined poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core shell particles with a moderately high solid content (49%) and particle diameters of less than 200 nm were prepared via seeded emulsion polymerization with a redox initiator and an anionic surfactant. Low-viscosity (less than 150 cps at 20 s-1) latex products were obtained by controlling the particle size distribution to within certain limits. Polymerization conversion and kinetics were followed gravimetrically and were adjusted so as to obtain recipes that could be scaled-up for industrial production. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

Abstract: The core–shell structure of a range of acrylic–acrylic latexes has been investigated by combining different specimen preparation methods with transmission electron microscopy (TEM), dark-field scanning transmission electron microscopy (DSTEM) and low-voltage scanning electron microscopy (LV-SEM), including the first reported use of LV-SEM to observe composite latex particles at ambient and subambient temperatures. Spin-coating of liquid latex dispersions directly onto TEM grids or SEM stubs is shown to be a relatively straightforward mean of avoiding film formation during specimen preparation. In conjunction with double staining techniques, it has been found to be particularly convenient for characterizing the fine structure of particles with diameters down to below 100nm. [Copyright &y& Elsevier]

Abstract: We have established a characterization method of a 100nm sized core–shell latexes composed of styrene–butadiene co-polymer. The core–shell structure was revealed by TEM observation of the latex film after modification with OsO4 vapor. Pyrolysis gas chromatography combined with mass spectrometry (Py-GC/MS) of the latexes showed the average chemical composition of the core–shell latexes. TOF-SIMS of the latex film gave the characteristic peak for styrene and butadiene. The peak intensities changed in accordance with the chemical composition of the latexes. Surface composition of the latex film, which corresponds to the composition of the shell part of the latexes, was estimated from this peak intensity ratio. From the combined analysis of Py-GC/MS and TOF-SIMS of the latexes, we successfully evaluated the chemical composition of both the core part and the shell part of latexes individually. As the results of characterization of some core–shell latex, it was revealed that the high degree of cross-linking is needed to synthesize the tailored core–shell latex. [Copyright &y& Elsevier]

Abstract: In this paper the effects of surface roughness and annealing temperature (T) of latex coating films on adhesion are discussed for the different stages of the film formation process. The surface free energy of latex films was assessed in terms of practical work of adhesion (W) (or adherence) using a custom-built adhesion-testing device (ATD), atomic force microscopy (AFM), and contact angle measurements. For preannealed latex films surface roughness averages (R a) were determined from AFM height images and were related to the values of W obtained from ATD measurements at room temperature. The results obtained using these tests exhibiting surface behavior on different length scales indicate a dependence of the measured adhesion on surface roughness and temperature, as well as on the length scale of the measurements. First preannealed samples were studied, which were obtained by heat treatment above the respective glass transition temperatures (T g). Increasing the temperature of preannealing resulted in a decrease of the adherence observed in ATD experiments at room temperature. However, on the nanoscale, using AFM, no significant variation of the adherence was observed. This observation can be explained by roughness arguments. Preannealing decreases roughness which results in lower adherence values measured by ATD while for essentially single asperity AFM experiments roughness has an insignificant effect. Specimens were also annealed over a constant period of time (90min) at different temperatures. At the end of the heat treatment, adhesion was measured at the treatment temperature by ATD. The amplified effect of temperature observed in this case on adherence is attributed to the combination of roughness decrease and increasing test temperature. In a third set of experiments completely annealed samples were studied by ATD as well as by AFM as a function of temperature. With increasing T values ATD showed a decrease in adherence, which is attributed to a decreasing surface free energy of the annealed films at elevated T values. AFM, on the other hand, showed an opposite trend which is assigned to increasing penetration of the tip into the tip/wetting polymer samples versus increasing temperature. Finally, annealing isotherms as a function of time were investigated by ATD in situ at different temperatures. This last set of experiments allowed us to optimize annealing time and temperature to achieve complete curing. [Copyright &y& Elsevier]

Abstract: In this work, the synthesis, properties of a thermal/pH-sensitive core-shell copolymer latex were studied and its potential application as a targeting drug carrier was also investigated, where the crosslinked copolymer of N-isopropylacrylamide (NIPAAm) and chitosan was synthesized by soapless dispersion polymerization as the core, and the copolymer of methacrylic acid (MAA) and methyl methacrylate (MMA) was prepared as the shell. The weight ratio of chitosan/NIPAAm and the concentration of crosslinking agent in feed had been changed to investigate their effects on the particle size, reaction rate, zeta potential, surface functional groups, and specific surface area of latex particles. The swelling and thermo-sensitive behavior of the film made from these core-shell latexes were also studied under different pH values of buffer solution. The model drug (caffeine) could be loaded inside the copolymer particles and protected from releasing through the transport process effectively. And the thermo-responsive property of these copolymer particles significantly enhanced the protein conjugation that showed the potential of the latex being applied on the targeting drug carrier. [Copyright &y& Elsevier]

The resolution of NMR velocimetry is inherently limited by random displacements due to molecular self-diffusion, and has so far not extended below a few tens of microns. We report here an extension to the nanoscale domain, a result achieved by the use of slowly diffusing, NMR-visible core-shell latex particles. These particles comprise an oil core surrounded by a solid polymer shell, making spheres of diameter 370 nm. Using these particles in the annulus of a concentric cylinder Couette cell, we have measured flow-induced displacements down to a few hundreds of nanometers, allowing the observation of the solid-to-liquid transition of a glassy system. We envisage new possibilities for NMR velocimetry as an experimental tool for colloidal chemistry and physics. [Copyright &y& Elsevier]

Heterogeneous latices of acrylic core–shell polymers were designed and prepared via a two-stage seeded emulsion polymerization for plastisol–gel of automotive underbody coatings and body sealers. 1,6-Hexanediol diacrylate (HDDA) was introduced to the rubbery core and/or the glassy shell with interpenetrating polymer network (IPN). The latices were characterized by submicron particle sizer, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The properties of plastisol–gels prepared by mixing the core–shell polymers and DOP/TCP plasticizers were investigated by testing the storage stability of plastisols and the mechanical properties of plastigels. These novel core–shell polymers represent a highly positive innovation and a wide application in automotive industry instead of the hazardous material PVC plastisol. [Copyright &y& Elsevier]

Protein purification by means of downstream processing is increasingly important. At the University of Twente a semi-continuous process is developed for the isolation of BSA out of crude protein mixtures. For this purpose an automated Affinity Cross-Flow Filtration, ACFF, process is developed. This process combines the advantages of both affinity adsorption, having high resolution, and microfiltration, for rapid and large continuous processing capacity. The overall process contains 4 sequential steps: affinity binding; purification; dissociation; regeneration. In the first step binding of the desired protein to a tailor-made ligand-immobilized particle is established. This temporary fixation of target proteins on a large entity allows us to wash out the unbound components in the purification step using high flux microfiltration membranes. After washing out the unbound proteins the target protein-ligand immobilized particle complex is dissociated by adding an appropriate salt. In a second filtration cycle the purified protein can be collected as the permeate. In the last step the ligand-immobilized particle is regenerated for the next cycle with buffer. Using this process it was possible to obtain the target protein BSA with a purity of more than 95%. [Copyright &y& Elsevier]

Polypyrrole latex (P(P)), synthesized in Redox polymerization of pyrrole, was used as seed for radical polymerization of acrolein initiated with K2S2O8. In this process the polypyrrole core/polyacrolein shell latex (P(P–A)) was obtained. Morphology of the surface of P(P–A) particles was investigated by atomic force microscopy (AFM). It was found that macromolecules of polyacrolein are not randomly distributed on the surface of polypyrrole but form patches. Apparently, attraction between macromolecules of poly-acrolein in the surface layer is high and the enthalpy of formation of polyacrolein macromolecule clusters is sufficient to compensate, at least, the negative entropy change due to ordering of these macromolecules. Thickness of the polyacrolein layer on the surface of polypyrrole particles, which were covered only partially with polyacrolein, was equal to only 1.6 nm (standard deviation σ= 0.2 nm) and thus, it was reasonable to assume that it corresponded to the monolayer coverage. [ABSTRACT FROM AUTHOR]

The redox polymerization of pyrrole, with ferric chloride as oxidant, carried out in the presence of polyvinylpyrrolidone (PVP), yielded polypyrrole latex particles. The polypyrrole latex was used, as seed, for the radical polymerization of acrolein. The resulting polypyrrole core/polyacrolein shell latex (poly(P/A)) was suitable for immobilization of up to 11 mg of human serum albumin (HSA) and/or 33 mg of human gamma globulin (γG) per 1 g of latex particles. [ABSTRACT FROM AUTHOR]